INSECTA. 387 



Family XXIV. Tentkredmeta s. Serrifera. Abdomen sessile, 

 continuous with thorax, covering the origin of posterior feet, cylin- 

 drical or ovato-oblong. Mandibles large, horny, acuminate, in- 

 curved, mostly tridentate. Maxillary palps mostly sexarticulate, 

 labials four-jointed or quadriarticulate. Labium cloven into three 

 lacinice. Wings both anterior and posterior furnished with dis- 

 tinct cells. Borer almost always occult, included in a bivalve 

 sheath, compressed, cultrate, mostly serrate, composed usually of 

 our setae (the upper one of other hymenoptera being here cloven to 

 tie base). Tibiae of anterior feet with two terminal spines. Larvae 

 similar to caterpillars) with mostly twenty-two or twenty feet, 

 eeding on leaves. 



Leaf-wasps. The larvae mostly eat leaves like caterpillars, some 

 live in gall-excrescences. These insects are often very destructive to 

 trees, and the knowledge of them is therefore very important to the 

 forester. Some also injure our potherbs. 



On this family, besides the Monograph of HAKTIG noted above and the 

 third part of the Forst-Insecten of KATZEBURG, may be consulted : KLUG, 

 Die Blattwespen der fabrizischen Sammlung; WIEDEMANN'S Zoologisckes 

 Magazin, I. 3, 1819, s. 84 91, Tab. n., and by the same, Uebersicht der 

 Tenthredinetce der (Berliner) Sammlung, in his Jahrbucher der Insekten- 

 Tcunde, I. Bd. 1834, 8vo, s. 223 253, Taf. n. figs. 5 10 ; G. DAHLBOM, 

 Clavis novi Hymenopterorum systematis adjecta synopsi larvarum scandina- 

 vicar. eruciformium, Lundse, 1835. 



A. Borer exsert. 



Xyela DALMANN, Mastigocera KLUGL Antennae thirteen-jointed, 



tvith fourth joint longest (equalling or surpassing in length the 



line terminal joints taken together). Borer of females of the 

 ength of abdomen. 



B. Borer occult. 



a) Antennae with numerous joints, (fifteen to thirty-six). 



Lyda FABE., HAETIG, Pamphilius LATE. Antennae setaceous 

 nineteen- to thirty-six-jointed). Kadial cells two, cubital four. 

 Posterior tibiae with three lateral spines. 



The larvae of this genus live together socially in a \veb ; they have, 

 besides the six horny feet on the thoracic segments, only two propellers 

 directed outwards at the hind part of the body. Comp. HARTIG 1. 1. 

 Tab. vn. figs, i 1 6, and RATZEBURG, Forst-InseUen. m. Tab. I. 



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